Yep.

I was at work during the earlier post. It was written over about a 2 hr period and I lost track a few times

 

usually needs good flow paths, and longer runs so that the momentum of the air can stuff more in. It's the intake version of exhaust scavanging. I'm still baffled by this one.

Matt

 

If I follow this correctly, then it does makes sense on a certain level, though I don't see it so much in the big picture. It becomes a matter of the path of least resistance, with a smaller filter (at least availible area), say of the foam variety there are thousands of little holes for the air to pass through, so the layer of air over the filter when only has a few paths will move quiker, giving the numbers a chance to jump up quicker though with a smaller filter the numbers may not get quite as high on the WOT. Its kinda (in very loose terms) a Venturi effect over the filter.

 

So, should anyone ever want to tackle this, someone could come up with some sort of mechanical baffle which would cover the filter at low RPMs and would uncover it at high RPMs... thus maximizing air flow at all speeds?

 

That or well... It won't be up with tomorrows numbers but I've had some ideas in the works, that if I can taclke the wohle car on speed zero bit, well lets just say I won't have any worries. Remember Achams (don't think I ever spell that right) razor, mechanical baffle or on off siwtch?

 

You know you really shouldn't give me a reason to do this stuff.....

 

Brewhahahahha... it's all in my evil plan!

First the baffle... next THE WORLD!!!!

 

Careful I just might, I've been biting my tounge today, but tomorrow looks like its gonna be very busy.

 

Now who's the tease?lol:

 

Kinda sounds like the JCS airbox, doesn't it?

 

Such is the process when words go into action, insulation is just he first step, by a long shot, think of an intake always having cold air foced into it, even when stationary the air temp entering the filter at or below abient; doing this work with the intakes has the wheels turning for even coming up with intake options and asking questions, like why would MINI cause air to go down then up then back down to get to the TB, or what would the effectiveness of a panel filter in place of the stock cowl sheild then a slowly decreasing diameter insulated tube back to the TB. Not that thats what I'm going to pursue but my mental wheels are turning and it feels good; my goals are improving the CAI by ensuring that air is cold and after I solve the diagnostic part of the equation that that air is also entering under pressure. Maximize wha tgets put into it, so we can get the most out of it.

 

No, that restricts air to the filter not surface area of the filter; for this to work as we (or at least I) understand it, its a change in surface area that adjusts the gain.

 

You can say "we".

For sure a limiting of surface area... NOT air.

 

Interesting... I had thought the JCW box did that too. Thanks for clarifying...

But I'm still not convinced that this is what is happening in my case... I can demonstrate less than ~10% restriction of the filter itself, maybe none, given that the thermal pad I'm using might not touch at all in areas where I can't reach to test it...

And there is huge airspace beneath and at the rear of the filter, and at least optimal airspace on the top and left sides...

In my figuring, the only thing that could be happening that might seriously restrict airflow into the filter is the vacuum effect of motion against the windshield as speed increases... What is restricted is all air from the engine compartment though.

Btw, drove it around with my wife's butt-dyno in the passenger seat. She loves the quieter SC... And I scared her with the power, so I guess that might confirm some change.

-- VBG

 

Occam's Razor

 

This sort of sounds like the air flow issues found with early 4-valve engines. It was found that with a large intake the slower air flow into the engine resulted in imperfect mixing of the air and fuel. This caused reduced power and torque.

The engineer's redesigned the intake manifold by splitting it and using a valve to keep half closed at lower speeds to increase the air flow speed. At higher engines speeds the valve opened.

 

There is no vacuum if I'm understanding your statement right.
Here's and old post you might enjoy

 

I'll be interested in any results. I'm very sure of what I found. I played around with this for weeks off and on. Sometimes forgetting for a bit what state I had left my experiment in. So although it's definitely not a double blind test it was definitely a "Do'h I forgot" blind test

For those interested I had simply made the sleeve from 6 mil plastic taped into a tube and used velcro strap to hold it in place.

On a side note here's another bit for conversation.

I recently moved from an Alta(which I had driven with for almost 3 years) to the HDI.
Bear I mind I had absolutely no expectations of a performance difference. I made the change simply because I didn't like the design of a CAI sealing against the hood.
I dynoed the car before and after. The results were me posting the infamous "My intake is better than yours" thread

The only difference I could tell between the 2 systems was that the HDI felt crisper at tip in.

Filter surface area again??

 

I've been thinking about what motor on brought to the table and started actually thinking about why MINI would design their stock airbox the way they did.

Maybe they aren't as big of idiots as some after-market companies make them out to be with their stock sox box.

A few more lame work-drawn images of the stock box...


The cowel in the back allows for the "fast air" effect that we've been talking about.
But once the car starts moving quickly...


You get a pressurized type system from the front port of the airbox.

Now why the loop-d-loop turn in the stock box...
The only reason I can think of it to utilize gravity as best as possible, but would gravity really have the big of a difference in this situation?

So if this seemingly is a good design... why do so many people put in the CAI? (myself included)

 

if you don't want to hear the motor.. If you want to run at red-line it's not a good design... The motor is starved for air....

Matt

 

But, if you increase the size of the hole to the cowl in the stock air box and put in a high flow filter (panel or cone), would you still consider the motor starved for air?

 

That loop-d-loop is definitely not for gravity or pressure effects. The pressure difference in air is so little, it's completely neglected in thermodynamic measurements concerning other fluids. It takes only 19(?) feet of water to equal the pressure of the entire atmosphere.

 

But if you increase the size of the cowl in the back, you are negating the "high velocity at take off" theory.

 

I'm not talking about making a huge hole or anything. Mine is currently 2.5 inches. The problem is determining the proper size of the intake area coming into the stock box to achieve the best balance of air flow and power. Perhaps the addition of a velocity stack on the intake?

 

Follow my link in post 117. You don't see measurable pressure in the cowl

That vent in the stock airbox may be there for a few reasons. Water drain, heat vent, sound, either for driver feedback or possibly to smooth air in the box, etc.

Just thinking in print